Method of splicing tubular articles



Oct. 18, 1955 w STRONG ET AL 2,720,908

METHOD OF SPLICING TUBULAR ARTICLES Filed Sept. 6, 1952 2 Sheets-Sheet lJUL/527727225 ZLZ'EZZEE z] 52352721;

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METHOD OF SPLICING TUBULAR ARTICLES Filed Sept. 6, 1952 2 Sheets-Sheet 2tates Patent 2,720,908 Patented Get. 18, 1955 METHOD OF SPLICIINGTUBULAR ARTHEFLES Walter .1. Strong and Amil A. Hanson, Qnyahoga Fails,@hio, assignors to The E. F. Goodrich (Company, New York, N. 25., acorporation of New York Application eptemher 6, 1952, fierial No.363,232

3 Claims. ((32. 154-414) This invention relates to the splicing ofthick-walled tubular articles of unvulcanized rubber material and isespecially useful in the splicing of tubular material in the manufactureof curing bags used in curing tires by use of internal pressure.

In the manufacture of pneumatic tires, a thick-walled bag of vulcanizedrubber is inserted within the unvulcanized tire casing, the assembly isenclosed within a mold cavity, and the bag is inflated while heat isapplied to the mold. The bag forces the tire casing to conform to themold and stretches the cord material of the tire.

Heretofore, in the manufacture of curing bags, a thickwalled tube ofunvulcanized rubber has been formed by extrusion, the tube has been cutto length and one end of the tube has been skived or beveled on theinside by paring away rubber with a hand knife. The other end has beenskived on the outside to fit within the first end. Both ends have thenbeen cemented and telescoped to gether. The annular bag has then beeninflated within a mold and vulcanized to shape. Difliculty has beenexperienced in obtaining satisfactory splices by the method heretoforeemployed as it has been difficult to obtain effective pressure on allparts of the splice, especially at the inner face of the tube wall. ithas been practically impossible to trim the telescoped ends of the tubeto an intimate fit throughout and the thick-walled tube has resisted byits stiffness the conforming of the tapered faces to each other, and anypressure fluid escaping into the seam counterbalances the internalpressure on the splice resulting in a bag having a defective splice.

The present invention aims to overcome the foregoing and otherdifliculties.

Objects of the invention are to provide an improved splice inthick-walled tubes, to provide adequate seaming pressure at all surfacesof the splice, to provide increased seaming pressure adjacent the boreof the tubular material, to simplify and render precise the operation ofpreparing the ends of the tubular material, and to facilitate the stepof holding the prepared ends in juxtaposition during joining.

These and other objects will appear from the following description andthe accompanying drawings.

Of the drawings,

Fig. 1 is a side elevation, partly broken away and partly in section ofa tube beveling apparatus of our invention and a portion of the beveledtube illustrating a step in one method.

Fig. 2 is a plan view of a clamping apparatus of our invention with theannular curing bag clamped therein illustrating another step of ourmethod.

Fig. 3 is a sectional view taken on line 33 of Fig. 2.

Fig. 4 is a side elevation of the spliced bag at the splice, parts beingbroken away and shown in section.

Fig. 5 is a partial section showing an additional step that may berequired.

According to our invention, the extruded tubular material for formingthe bag is formed with a uniformly conical convex face at each endthereof so that the end faces project at the bore of the material beyondtheir peripheral surfaces. The cleaned and preferably cemented ends arethen pressed against each other by clamping means so that greaterpressure is exerted on the seam at the bore of the tube than at itsperiphery. Strip unvulcanized rubber material may be wound into anyunclosed peripheral portion of the seam to fill it, and the bag isvulcanized in a mold under internal pressure in the presence of appliedheat.

Referring to the drawings, and first to Fig. 1 thereof, this shows apower-driven rotatable spindle 10, driven by means such as electricmotor 11 and having fixed thereto for rotation therewith an abrasivewheel 12. The wheel may be of emery, Carborundum, or other coarseabrasive material and has a concavely conical side face 14 exposed inthe outboard direction for grinding a convex conical face on the end ofthe thick-walled unvulcanized rubber tube 15. To properly center andguide the tube 15 concentric with the wheel 12 a pilot bushing 18 havingan outer diameter fitting the bore of the tube 15 is mountedconcentrically on the spindle 10 as by an antifriction ball bearing race17. The bushing is free to rotate relative to the spindle 10 and has abeveled shoulder 19 at the outboard end to facilitate entering the boreof the tube 15'.

The tube 15 is held by the hand 21 of an operator against rotation whileits bore is passed over the pilot bushing 1&5. As the end of the tube isforced against the conical face 14 of the wheel 12, the rubber materialis ground away to provide a convex conical surface 21 thereon concentricwith the tube. Furthermore, the abrasive action of the wheel 12 cleansand heats the end of the tube.

The opposite end of the tube 15 is treated in the same manner so thatboth ends of the tube are convexly conical.

The tubular article is then placed in a clamping mechanism illustratedin Fig. 2. The clamping mechanism comprises a supporting plate having ahinge pin 31 projecting thereabove. Semi-circular clamping jaws 32, 33are hinged to pin 31 for movement toward and from each other. Theseclamping jaws each consist of a flat wall 34 parallel to plate 30 and anarcuate wall 35 extending thereabove for engaging the perimeter of thetube. Hinge lugs 36 secured to the jaws engage the pin. A pair ofhandles 37, 38 are attached respectively to the jaws 32, 33 and areshown as representing means whereby the jaws may be forced toward andfrom each other, it being understood that other means such asfluid-pressure operated cylinders may be used for operating them. Theinterior surfaces of the jaws may be shaped to conform to the tubewalls. However, it has been found that this is not necessary but may bedesirable near the splicing position. For this purpose the jaws may beformed with inwardly turned flanges 4t), 41 near the 'unpivoted endsthereof.

The tube prepared by beveling its end to provide convex end faces ashereinbefore described is bent to annular shape and placed between thejaws 32, 33 with the jaws spread apart. Prior to clamping of the tubethe convex faces of the ends of the tube are preferably cleaned with asolvent of unvulcanized rubber or a thin layer of rubber cement may beapplied thereto, in order that initial joining may be obtained prior tovulcanization. The handles 37, 38 or other pressure means are thenoperated to close the jaws forcing the tube ends into endto-endengagement. As the tube ends have convex conical surfaces, theirportions adjacent the bore of the tube receive the greatest initialpressure and such pressure causes tube material to move radiallyinwardly of the bore proper, increasing the wall of the tube at thebore, as seen at 42, Fig. 4.

After force has been applied to the clamping jaws to force the faces ofthe tube ends into initial adhering contact, the annular tube article isremoved from the clamping apparatus. If, as seen in Fig. 5, a gap existsbetween the convex end faces at the periphery of the splice, a thinstrand 43 of unvulcanized rubber material is then wound in the gap tofill it. The dimensions of the clamp are such that the ends thereof arespaced at the joint in the tube to facilitate adding strand 43. Thetubular article is then confined in a closed mold (not shown) and isinflated and vulcanized. This inflation may be accomplished by means ofa valve stem secured to the wall of the tube before the tube is splicedas is well known in the art.

The spliced tube is illustrated in Fig. 4 where the ends 15a, 15b of thetube 15 have been spliced at 150. Due to the fact that the end faces ofthe tubular material were originally convexly conical, the thickness ofthe splice 150 is greater than the thickness of the tube wall andprovides a strong splice in which adhesion of the end surfaces of thematerial at the bore of the tube are assured by the fact that they areadhered in advance of the surfaces radially outward thereof and havebeen subjected to greater pressure in splicing.

Variations may be made without departing from the scope of the inventionas it is defined by the following claims.

We claim:

1. The method of splicing tubular articles of unvulcanized rubbermaterial which comprises forming convex conical end faces on the tubularmaterial, pressing two of the convex end faces against each other inaxial alignment to cause progressive engagement of the end material fromthe radially inner margin of each convex conical end face toward theradially outer margin thereby causing material to flow radiallyinwardly, and vulcanizing the spliced material.

2. The method of splicing tubular articles of unvulcanized rubbermaterial which comprises forming convex conical end faces on the tubularmaterial, pressing two of the convex end faces against each other inaxial alignment to unite them to each other adjacent the bore of thematerial causing progressive engagement of the end material from theradially inner margin of each convex conical face toward the radiallyouter margin thereby causing radially inward flow of the end materialand leaving a peripheral groove, filling the groove between the endfaces with unvulcanized rubber material in strip form, and vulcanizingthe spliced material.

3. The method of forming a unitary toroidal tube of rubber materialwhich comprises the steps of forming convex conical end faces on astraight length of tubular rubber-like material, confining and bendingthe tubular material to cause it to assume a toroidal shape and to alignits end faces with each other, pressing the two end faces adjacent thebore of the tube together causing progressive engagement of the endmaterial from the radially inner margin of each convex conical facetoward the radially outer margin thereby causing radially inward flow ofthe end material, confining the annular body so formed within anenclosing mold, and vulcanizing the annular body.

References Cited in the file of this patent V UNITED STATES PATENTS1,828,925 Cristopherson 2.. Oct. 27, 1931 1,998,633 Nichols Apr. 23,1935 2,073,079 Thelar Mar. 9, 1937 2,115.908 Fox May 3, 1938 2,273,463Campbell et a1 Feb. 17, 1942 2,339,559 Charnes Ian. 18, 1944 2,474,511Bacon June 28, 1949 2,498,953 Glynn Feb. 28, 1950 2,565,703 Strong Aug.28, 1951

